Angle-measuring attachment for saws



Patented Aug. 10, 192s.

' Joniv L. mason, oF onIcAeo, ILLINo'Is.

ANGLE-MEASURING ATTACHMENT FOR. sAWs;

Application filed July 9, 1923. "Serial No." 650,561.

This inventionrelates to combination and convertible tools and the like and especially to handsaws adapted for measuring angles related to the vertical, such for instance as the inclination of rafters and other house parts. Heretofore it has been customary, for the most part, to use entirely separate and independent tools for sawing and for measuring angles respectively, although numerous attempts have been made to provide practical angle-gage attachments, and some such devices have had great utility in their specific fields.

The main objects of this invention are to provide an improved form of angle-gage attachment adapted for use on straight-edged tools, especially saws; to provide such an attachment adapted by operation of gravity for measuring any and all angles relative to the vertical position; and to provide such an attachment adapted for ready hang-on and lift-oil application to and disconnection from the saw.

An illustrative embodiment of this invention is shown by the accompanying draw-v ings, in which Fig. 1 is a side elevation of a handsaw showing the gage attachment in place;

Fig. 2 is an enlarged front View of the pendulous index finger;

Fig. 3 is a side view of said finger with part of the saw blade shown in section; and

Fig. lis a greatly enlarged section on the line 4-4 of Fig. 2, and also shows part of the saw blade in section.

In the construction shown in the drawings, the saw blade 1, having a straight back 2, is provided with a gravity gage 3 of the pendulous variety. I

Said gage 3 includes an index fingers. raving a medial pivot 5 and a massive head 6 on the lower end opposite from the upwardly projecting index tip 7.

Concentric with the central aperture 8 in said blade 1 is a gage circle 9 with angle indices 10 suitably numberedto facilitate reading. This scale 'may well read from zero to ninety in each quadrant, as shown. The zero positions are preferably assumed to be at right angles relative to the back edge 2. Hence, each of the ninety degree positions of gravity finger l is parallel with the back. The circle 9, index marks 10 and the numerals may we'll be etched in metal efthe blade, er they may heather Wise applies as may he fennel The pivot preferably in the formof a short pin or stud having a stop flange 11 and arranged with its shank part 12 set rigidly in the finger hole 13 as by riveting at 12', the finger 4 being enlarged somewhat at this point. There is a deep groov 14 surrounding the journal part 15 and lying between the flange 11 and the retaining head 16. This head is conoidal to facilitate assembling. The index finger'd may be readily removed by lifting out of engagement at 8 when the measurements in any instance are completed or when the saw is to be used for cuttin purposes.

Whenever the angle-gage accessory is to be used the finger 4 is attached by slipping the head 16 through the blade aperture 8 whereupon the attachment drops into place by gravity. Then supposing that it is desired to determine whether or not a floor sill is in a level position, the saw back is applied thereto with the blade held in a verticalplane, as in Fig. 1, and any deflection of the index tip 7 from Zero will measure the angle of the sill relative to the horizontal. Again supposing that it is desired to determine the angular position of a rafter. In this instance the saw blade is turned and held in a vertical plane with its back inclined and held up against the rafter, whereupon gravity will cause the finger tip 7 to measure the desired angle on one pf the quadrants shown adjacent to the back 2, as will be understood without further explanation. Vhen the saw is to be used as such, the index plumb 4 is removed by lifting from its pivotal bearing in the blade aperture 8 and placed in the tool box until another vertical angle is to be measured.

It will be seen that this improvement adds nothing to the weight of the saw when used as such, and it has all of the practical applications of a spirit level, and is more sensitive and accurate. Moreover, it is simple and inexpensive and there is nothing to get out of order.

Although but one specific embodiment of this invention has been herein shown and described, it will be understood that numerous details of the construction shown may be altered or omitted without departing I claim i 1. A stra1ght-baclt circular l blade having a snmhination with.

index plumb having a lateral supporting pivot With a head thereon small enough to pass through said perforation and adapted to prevent accidental Withdrawal in normal use, said plumb having an index finger, and said blade having an angleweadingsoale in functional relation to said plumb.

2. A straight-edged saw in detachable combination With a medially-pivoted rigid plumb attachment, said saw having an an: 1

gular scale surrounding the point of attachment, to Which scale the light upper end of said attachment is ,readably related When assembled for use for measuring vertical angles.

Signed at Chicago this 7th day of July,

JOHN L. LARSON. 

